This invention relates to an improved structure for unloading bulk quantities of dry product from a railroad hopper car in a fast and efficient manner.
Railroad hopper cars are well known in the art and are commonly used to transport bulk quantities of dry product from one location to another. A typical railroad hopper car includes a sealed container that is supported on a pair of spaced apart wheel assemblies. The container has upper surface that is usually provided with a plurality of spaced apart hatches to facilitate the loading of the product into the container. The lower portion of the container is often segmented into a plurality of tapered discharge sections to facilitate the unloading of the product therefrom.
In some instances, the unloading of the railroad hopper cars occurs solely under the influence of gravity. To accomplish this, a valve provided on the bottom of the tapered discharge section of the container is opened, allowing the product to flow downwardly therethrough into a receiving apparatus. Such gravity unloading is simple and inexpensive from an equipment standpoint, but has been found to be rather inefficient. This is because the product unloads from the container at a relatively slow rate, which undesirably increases the amount of time and resources required to empty the product from the container. Also, portions of the product often coalesce and adhere to the interior of the container. When this occurs, portions of the product do not unload under the sole influence of gravity, thus requiring additional time and effort to dislodge such portions for unloading.
To address these problems, some railroad hopper cars are provided with equipment that introduces pressurized air within the container during the unloading process. The introduction of pressurized air within the container increases the magnitude of the air pressure therein, thus positively urging the product out of the container at a rate that is faster than if the product was unloaded solely under the influence of gravity. Additionally, the flow of pressurized air within the container tends to stir up or fluidize the product therein so as to minimize the occurrence of coalescence and adherence of the product to the interior of the container. Thus, the benefits of pressure differential unloading have been found to outweigh the additional costs associated with the additional equipment that is necessary to perform it.
Although railroad hopper cars provided with this pressure differential equipment have functioned successfully for many years, the occurrence of coalescence and adherence of the product to the interior of the container remains a concern. Furthermore, it would be desirable to provide a structure for unloading product from a is railroad hopper car that is even faster than known pressure differential unloading techniques.